Added essential columns in the data to make it feast friendly

[aniketpalu]

This PR Includes:

• Added entity_id column which represents entities by which transactions are executed. Each entity has 3-4 repeating transaction in each CSV.
• Added created_timestamp column which represents the timestamp of creating the records.
• Added event_timestamp column which represents the time of the transaction.

Note: There is no relation between created_timestamp & event_timestamp. This modification is done for making the data feast friendly.